1. Field of the Invention
The present invention generally relates to lock and key assemblies. More specifically, the present invention relates to an improved electronic lock and key assembly.
2. Description of the Related Art
Electronic locks have a number of advantages over normal mechanical locks. For example, electronic locks may be encrypted so that only a key carrying the correct code will operate the lock. In addition, an electronic lock may contain a microprocessor so that, for example, a record can be kept of who has operated the lock during a certain time period or so that the lock is only operable at certain times. An electronic lock may also have the advantage that, if a key is lost, the lock may be reprogrammed to prevent the risk of a security breach and to avoid the expense associated with replacement of the entire lock.
One drawback of certain electronic locks is that they use a power supply to function properly. Typically, locks of this type are unable to use conventional alternating current (AC) power supplies, such as from wall outlets, due to the inherit lack of security and mobility of such power supplies. Batteries may be used instead, but batteries require constant replacement or recharging. If a battery dies, a lock might fail to function and thereby create a significant security risk. Electromagnets may also be employed, but the bulk of such devices in some instances limits the potential use of electronic locks to larger-scale applications.
One solution to these drawbacks is to place a power source such as a battery in the key instead of in the lock. This arrangement allows the lock to remain locked even in the absence of a power supply. Placing a battery in the key also allows the battery to be charged more easily because keys are generally more portable than locks.
When batteries are used in the key, electrical contacts are typically employed to transfer power and data from the key to the lock. However, electrical contacts suffer from the drawback of being susceptible to corrosion, potentially leading to failure of either the key or the lock. Moreover, if separate inductors are used instead to transfer both power and data, magnetic interference between the inductors can corrupt the data and disrupt power flow to the lock.